Myelination 2 Flashcards
Role of Krox20?
Requirement for myelination
Role of Pax3?
Involved in upregulation of proteins that are needed in the myelin sheath
e.g. controls MBP (myelin basic protein) expression
Which adhesion molecule required for initiation of myelination is only present in schwann cells?
L1
Which adhesion molecule required for initiation of myelination is only present in oligodendroytes?
Neurofascin-155
Role of periaxin?
Cytoskeletal-linking protein in schwann cells
What is autocrine survival?
A cell produces its own survival factors
WHich factors does a schwann cell produce once it is in contact with an axon?
neurotrophin 3, insulin-like growth factor 2, PDGF-BB
Role of neurotrophin 3, insulin-like growth factor 2, PDGF-BB n schwann cells?
Mediation of autocrine survival
What happens to the mobility of schwann cells and oligodendrocytes once they start myelination?
They become immobile
What happens to the cytosol in the myelinating cells once myelination begins?
It must be mushed back out into the cell body
What are the cell adhesion proteins for the two myelinating cells?
Schwann cells–> P0
Oligodendrocytes–> PLP (proteolipid protein)
Role of cell adhesion proteins in myelination?
Making contact between diff layers of the myelin sheath
Role of myelin basic protein and myelin associated glycoprotein?
Their charge excludes everything else out of the membrane
What charge does myelin basic protein have?
+ve
What happens to animals with defective myelination?
Motor control issues, general nervous system issues
What are the regions associated with the nodes of ranvier?
Node, paranodal regions, juxtaparanodal regions
Node of ranvier characteristics?
Voltage-sensitive Na+ channels
Paranodal regions characteristics?
Contains contactin, Caspr (schwann cells have nuerexin)
Role of contactin, Caspr and nuerexin?
Transmembrane proteins that prevent movement of Na+ and K+ ion channels in plasma membrane
Juxtaparanodal characteristics?
High concs of K+ channels
How is high resistance to electrical activity created in the ends of the nodes?
Folds of the membrane with tight connections to the axon
What happens to sodium channels as NoRs narrow and mature?
Their density increases
What happens to potassium channels as the NoR matures?
They first appear at nodes, before moving to paranodes and juxtaparanodes as the structure matures
